Look-ahead system and method for pan and zoom detection in video sequences

1. A method of detecting at least one of a pan and a zoom in a video sequence, comprising: receiving a video sequence, the video sequence comprising a plurality of frames; determining a set of motion vectors for each frame in the plurality of the frames; determining a motion angle for each motion vector; detecting a scene cut in the plurality of the frames based on the motion vectors of the frames; selecting a set of frames from the plurality of the frames responsive to detection of the scene cut; identifying at least two largest regions in each frame, wherein a first largest region includes motion vectors having a first orientation and the second largest region includes motion vectors having a second orientation; determining percentages of each frame covered by each of the at least two largest regions; determining a statistical measure of the motion vectors for at least one of the two largest regions using a look-ahead detector; and comparing the percentages and statistical measure to threshold values to identify whether the plurality of frames includes at least one of a pan and a zoom.

2. The method of claim 1 , wherein selecting a set of frames from the plurality of the frames responsive to detection of the scene cut comprises: selecting a set of video frames from the plurality of the frames of that includes all the frames in the video sequence up to and including a frame just before the detected scene cut.

3. The method of claim 1 , wherein frame differences and motion vectors of the plurality of the frames are used to detect a scene cut.

4. The method of claim 1 , wherein the motion angles are computed in one from the group of coordinate systems consisting of polar, Cartesian, spherical and cylindrical coordinate systems.

5. The method of claim 1 , wherein the percentages of each frame covered by the at least two largest regions are determined from the number of pixels in each region as a percentage of the total number of pixels in a frame.

6. The method of claim 1 , wherein the statistical measure is a variance of the motion angles of the motion vectors within at least one of the identified two largest regions in the frame.

7. A non-transitory computer-readable storage medium storing executable computer program code for detecting at least one of a pan and a zoom in a video sequence, comprising computer program code for: receiving a video sequence, the video sequence comprising a plurality of frames; determining a set of motion vectors for each frame in the plurality of the of frames; determining a motion angle for each motion vector; detecting a scene cut in the plurality of the frames based on the motion vectors of the frames; selecting a set of frames from the plurality of the frames responsive to detection of the scene cut; identifying at least two largest regions in each frame, wherein a first largest region includes motion vectors having a first orientation and the second largest region includes motion vectors having a second orientation; determining percentages of each frame covered by each of the at least two largest regions; determining a statistical measure of the motion vectors for at least one of the two largest regions using a look-ahead detector; and comparing the percentages and statistical measure to threshold values to identify whether the plurality of frames includes at least one of a pan and a zoom.

8. The computer-readable storage medium of claim 7 , wherein the computer program code for selecting a set of frames from the plurality of the frames responsive to detection of the scene cut comprises code for: selecting a set of video frames from the plurality of the frames of that includes all the frames in the video sequence up to and including a frame just before the detected scene cut.

9. The computer-readable storage medium of claim 7 , wherein frame differences and motion vectors of the plurality of the frames are used to detect a scene cut.

10. The computer-readable storage medium of claim 7 , wherein the motion angles are computed in one from the group of coordinate systems consisting of polar, Cartesian, spherical and cylindrical coordinate systems.

11. The computer-readable storage medium of claim 7 , wherein the percentages of each frame covered by the at least two largest regions are determined from the number of pixels in each region as a percentage of the total number of pixels in a frame.

12. The computer-readable storage medium of claim 7 , wherein the statistical measure is a variance of the motion angles of the motion vectors within at least one of the identified two largest regions in the frame.

13. A method of detecting at least one of a pan and a zoom in a video sequence, comprising: detecting motion vectors to detect a scene cut in a plurality of frames; selecting a set of frames from the video sequence in response to detection of a scene cut; identifying at least two regions in each selected frame, a first region having motion vectors of a first orientation and a second region having motion vectors of a second orientation; determining amounts of each frame covered by each of the at least two regions; and comparing the detected amounts to threshold values, and based on comparisons, classifying the video sequence as having a pan or zoom.

14. The method of claim 13 , wherein selecting a set of frames from the plurality of the frames responsive to detection of the scene cut comprises: selecting a set of video frames from the plurality of the frames of that includes all the frames in the video sequence up to and including a frame just before the detected scene cut.

15. The method of claim 13 , wherein frame differences and motion vectors of the plurality of the frames are used to detect a scene cut.

16. The method of claim 13 , wherein the motion angles are computed in one from the group of coordinate systems consisting of polar, Cartesian, spherical and cylindrical coordinate systems.

17. The method of claim 13 , wherein the amounts of each frame covered by the at least two regions are determined from the number of pixels in each region as a percentage of the total number of pixels in a frame.